Many large buildings, such as warehouses, shopping malls, and the like, are constructed with a steel super-structure that is supported at predetermined intervals atop vertical steel columns that are embedded at their bases within and extend upwardly from the concrete floor slab of the building. When constructing such buildings, concrete footings are generally cast in the ground at the prospective locations of the support columns with the footings having upper surfaces bearing anchor bolts to which the column bases are ultimately secured.
When the footings have thoroughly hardened, the vertically extending steel support columns are mounted thereto by means of the anchor bolts and the remaining steel super-structure of the building is constructed atop the columns. With the super-structure in place, box-shaped wooden forms known as column block-outs are typically built upon the footings surrounding and isolating the support column bases. The floor of the building is then prepared by grading, leveling, and compacting subbase material throughout the floor expanse to a predetermined depth. The subbase is compacted around and against the exterior surfaces of the wooden column block-outs, which isolate the column bases from the subbase material. The concrete slab is then poured on top of the subbase to the upper rims of the wooden forms and allowed to harden thoroughly. In this way, isolation pockets are formed in the floor slab around the bases of the support columns such that the column bases are isolated from the surrounding subbase material and concrete slab. The super-structure of the building can then be precisely aligned by appropriate adjustment of the column bases on their anchor bolts.
With the super-structure precisely aligned, the wooden forms that created the isolation pockets in the floor slab are forcibly removed and the remaining voids are filled with concrete, which provides stability and additional anchoring for the columns, protects the column bases from corrosive elements, and completes the concrete floor of the building. In addition, crack control joints are usually cut in the concrete floor slab with the crack control joints extending between adjacent isolation pockets to provide for controlled cracking of the slab as it expands and contracts with changing temperature.
While the just described method of constructing isolation pockets has been used for years with a measure of success, it nevertheless embodies numerous inherent problems and shortcomings. The mere construction and placement of the wooden forms about the bases of support columns, for example, can be extremely time consuming and wasteful, particularly in very large buildings that may include hundreds of support columns. In addition, the removal of the forms once the surrounding slab has hardened can be even more time consuming and usually results in the destruction of the form and in some cracking and chipping of the concrete floor slab around the lips of the isolation pockets.
In addition to being time consuming and wasteful, prior art techniques utilizing removable wooden forms can and sometimes do result in serious structural problems. For example, when the wooden form is removed so that the isolation pocket can be filled with concrete, the dirt and gravel that typically makes up the subbase beneath the floor slab often becomes dislodged and falls into the isolation pocket creating a partial void beneath a portion of the slab. Such dislodging of the subbase material is virtually unavoidable since the wooden form usually must be removed forcefully with blows from hammers and the like. The long term result can be a deterioration in the strength of the slab and a future collapse thereof in the event a heavy weight, such as a forklift truck, is moved onto the weakened area of the slab.
Another problem with current methods is the inherent requirement that the isolation pockets themselves be filled with concrete after the main slab has hardened and the wooden forms removed. Since the concrete slabs of most buildings will not support the weight of the concrete truck, the isolation pockets typically must be filled manually from wheelbarrows that are trucked by hand from a remotely located concrete truck across the floor slab to the locations of the isolation pockets. Again, this process is extremely labor intensive and thus wasteful of valuable time and money.
Thus, a continuing and heretofore unaddressed need exists for a method and apparatus for constructing isolation pockets that overcomes the problems and shortcomings of the prior art by eliminating wasteful form construction and removal, preventing the dislodging of subbase material in the region of isolation pockets, and eliminating the requirement that the isolation pockets themselves be filled with concrete after the main slab has hardened. It is to the provision of such a method and apparatus that the present invention is primarily directed.